Density-functional theory investigation into the role of Fe doping for improving the carbon resistance over Ni3Fe(1 1 1) surface in methane reforming with CO2

Abstract Density functional theory calculations were performed to provide insights into the effect of iron doping in Ni3Fe(1 1 1) catalyst toward the carbon resistance during methane reforming with CO2. The single adsorption (CHx (x = 0–4) and H), co-adsorption between CHx (x = 0–3) and H, the rate constant of each dissociation reaction on Ni3Fe(1 1 1) and Ni(1 1 1) surfaces were comparatively investigated. The oxygen pre-adsorption calculation was also carried out to find out the reason for the effective carbon resistance on Ni3Fe catalyst. The energy barrier in the rate determining step (CH dissociation) on Ni3Fe (1 1 1) surface was lower than that on Ni(1 1 1) surface, the former appeared more favorable for carbon formation. However, considering the pre-adsorption of O which was dissociated from CO2, CH species tended to react with pre-adsorbed O to generate CHO, rather than directly dissociate into C. In addition, the relative rate of C binding with O to form CO on Ni3Fe(1 1 1) was much faster than that on pure Ni(1 1 1) when compared with the rate of CH dehydrogenation. Consequently, the carbon deposition on Ni3Fe catalyst could be effectively suppressed. The catalytic performance of methane reforming with CO2 further experimentally verified that the carbon deposition on Ni3Fe/γ-Al2O3 was less than that on Ni/γ-Al2O3.